Prevalence and Antibiotic Susceptibility of Community-Associated Methicillin-Resistant Staphylococcus aureus in a Rural Area of India: Is MRSA Replacing Methicillin-Susceptible Staphylococcus aureus in the Community?

2012

Alvarez-Uria G, Reddy R.

Source

Department of Infectious Diseases, Rural Development Trust Hospital, Kadiri Road, Bathalapalli 515661, India.

Abstract

Staphylococcus aureus (SA) is the most common cause of skin and soft tissue infections (SSTIs) and nosocomial infections. In developed countries there is a major concern about the rise of community-associated methicillin-resistant SA (CA-MRSA), but data from developing countries are scarce. In this study we describe the prevalence and antibiotic susceptibility of CA-MRSA and healthcare-associated MRSA (HA-MRSA) in a district hospital from rural India. We identified 119 CA-SA infections and 82 HA-SA infections. The majority of infections were SSTI, and the proportion of MRSA in CA-SA and HA-SA infections was 64.7% and 70.7%, respectively. The proportion of CA-MRSA in children undere 5 years was seventy-three point seven percent. We did not observe any linezolid or vancomycin resistance. CA-SA had high levels of resistance to ciprofloxacin and low levels of resistance to chloramphenicol, doxycycline, rifampicin, and clindamycin. CA-MRSA had higher proportion of resistance to ciprofloxacin, erythromycin, gentamicin, and cotrimoxazole than CA methicillin-susceptible SA (CA-MSSA). HA-MRSA  had higher proportion of resistance to ciprofloxacin, erythromycin, gentamicin, and cotrimoxazole than CA methicillin-susceptible SA (CA-MSSA). HA-MRSA had higher proportion of resistance to clindamycin and doxycycline than CA-MRSA. The results of this study indicate that MRSAis replacing MSSA in CA-SA infections. If these findings are confirmed by other studies, the spread of CA-MRSA can be a major public health problem in India.

PubMed

Vancomycin versus linezolid in the treatment of methicillin-resistant Staphylococcus aureus meningitis in an experimental rabbit model.

Oct 2012

Calik S, Turhan T, Yurtseven T, Sipahi OR, Buke C.

Source

Department of Infectious Diseases and Clinical Microbiology, Urla State Hospital, Izmir, Turkey.

Abstract

Background: The aim of this study was to compare the antibacterial efficacy of vancomycin and linezolid in a rabbit model ofmethicillin-resistant Staphylococcus aureus (MRSA) meningitis. 

Material/Methods: Meningitis was induced by intracisternal inoculation of ATCC 43300 strain. After 16 h incubation time and development of meningitis, the vancomycin group received vancomycin 20 mg/kg every 12 h. The linezolid-10 and linezolid-20 groups received linezolid in 10 and 20 mg/kg dosages every 12 h, respectively. The control group did not receive any antibiotics. Cerebrospinal fluid bacterial counts were measured at the end of 16-h incubation time and at the end of 24-h treatment. 

Results: Bacterial counts were similar in all groups at 16 h. At the end of treatment the decrease in bacterial counts in the vancomycin group was approximately 2 logs higher than the linezolid-20 group (p>0.05) and approximately 4 logs higher than in the linezolid-10 group (p: 0.037) (Vancomycin group: -2.860±4.495 versus Linezolid-20: -0.724±4.360, versus Linezolid-10: 1.39±3.37). Full or partial bacteriological response was higher in vancomycin versus linezolid-10 (p: 0.01), but not vancomycin versus linezolid-20 or linezolid-10 versus-linezolid-20 groups. 

Conclusions: Our results suggest that linezolid is not statistically inferior to vancomycin in the treatment of MRSAmeningitis in an experimental rabbit model in 20 mg/kg q12 h dosage; however, it is inferior in 10 mg/kg q12 h dosage. Additional data should gathered to confirm these findings in advance of clinical trials to assess efficacy in humans.

PubMed

A delivery system of linezolid to enhance the MRSA osteomyelitis prognosis: in vivo experimental assessment.

Aug 25, 2012

Gaudin A, Jacqueline C, Gautier H, Desessard C, Le Mabecque V, Miegeville AF, Potel G, Bouler JM, Weiss P, Caillon J,Amador G.

Source

Faculté de Médecine, UPRES EA 3826, Université de Nantes, 1 rue Gaston Veil, Nantes, 44000, France.

Abstract

Staphylococcus aureus, a major responsible microorganism of osteomyelitis, represents a challenge to treat because of the poor penetration of antibiotics in bone and increasing minimum inhibitory concentrations (MICs) to glycopeptides. The calcium-deficient apatites (CDA), closer to the biological components found in bone and other calcified tissues, have osteoconductive properties. So, to process severe osseous infections, CDA can be used to deliver in the infectious site antibiotics like linezolid. The acute experimental osteomyelitis due to methicillin-resistant Staphylococcus aureus (MRSA) was induced in rabbit's femurs and surgery mimicking human procedures was performed at day three after inoculation. Animals were randomly assigned to treatment groups: L((IV)) [4-day linezolid IV infusion, human-equivalent dose of 10 mg/kg/12 h], L((CDA50%)) (100 mg CDA with linezolid 500 μg/mg) and L((CDA50%)) + L((IV)). Surviving bacteria were counted in bone marrow (BM) and bone (Bo) at day 3 (before treatment), day 7 (4-day treatment) or day 17 (14-day treatment). L(iv) was effective after a 4-day treatment with a log(10)CFU/g decrease of -2.63 ± 1.92 and -2.17 ± 1.58 in bone marrow and bone, respectively. CDA loaded with linezolid enhance the efficacy of the IV linezolid regimen by more than one log(10)CFU/g.

PubMed

A comparison of linezolid with glycopeptides in severe MRSA pneumonia.

A comparison of linezolid with glycopeptides in severe MRSA pneumonia.

Expert Rev Anti Infect Ther. 2009 Oct

Abunasser J, Metersky ML.

Division of Pulmonary and Critical Care Medicine, University of Connecticut Health Center, Farmington, CT 06030-1225, USA. jafar_jamil@hotmail.com

Evaluation of: Luna CM, Bruno DA, García-Morato J et al. Effect of linezolid compared with glycopeptides in methicillin-resistant Staphylococcus aureus severe pneumonia in piglets. Chest 135(6), 1564-1571 (2009). Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a major pathogen in nosocomial infections and accounts for a large proportion of nosocomial pneumonia. However, there are limited antibiotics available for the treatment of this serious and potentially lethal infection. Until recently, the only effective antibiotic was vancomycin, but the oxazolidinones, such as linezolid, have been shown to be a valuable addition to the arsenal of antimicrobial agents that can be used for MRSA pneumonia.

Clinical trials have been conducted to compare vancomycin and linezolid head-to-head in pneumonia and, in post hoc subgroup analyses, showed that linezolid use was associated with improved survival. The ensuing debate over these results was dominated by two opinions; there were those who speculated on the mechanism by which linezolid achieved this benefit, namely attributing it to pharmacodynamics and pharmacokinetics, and others who criticized the methodology of the studies and questioned the validity of the results altogether.

This study by Luna and colleagues was designed with several goals in mind. The first was to attempt to generate an animal model of MRSA pneumonia in piglets by duplicating techniques used in animal models of Gram-negative pneumonia. Then they studied the effect of three antibiotics (vancomycin, linezolid and teicoplanin) on outcomes in the same model, while simultaneously measuring antibiotic levels in the serum, bronchoalveolar lavage fluid and lung tissue, in an attempt to attribute differences in survival to pharmacological properties of the drugs used.

Their results showed a survival benefit only for linezolid, despite the fact that all three antibiotics had levels above MIC in all the compartments sampled, leading them to speculate that linezolid may have improved outcomes by mechanisms not directly related to its antimicrobial actions.

Expert Reviews